1. Field of the Invention
This invention relates to an analog touch tablet for the outputting of data to a computer or other graphics display device which translates a particular position or area touched on the tablet to the x-y axis coordinates of the position pressed by a user's finger or stylus. More particularly it is directed to a simpler non-electronic passive touch tablet capable of being manufactured at appreciably less expense.
2. Description of the Prior Art
Various U.S. patents show resistance measuring devices for determining x-y coordinates of a touch point. Several of these are listed and discussed in the related applications filed 3/15/83. U.S. Pat. No. 3,207,905 broadly shows the use of interdigitated conductive pathways in touch-sensitive keyboards where a human body impedance completes the circuit switch. U.S. Pat. No. 3,959,585 is illustrative of a resistance coated pair of spaced sheets in a stylus-operated tablet which outputs x- and y-axis coordinate readings. In general these prior art devices utilize a voltage potential and multiplexing techniques where first the x-axis reading and then the y-axis reading is obtained. This necessitates relatively expensive and complex electronic circuitry to effect such functions, including normally an analog-to-digital converter. Related application Ser. Nos. 06/475,418 and 06/475,419 disclose a three-layer tablet which has simultaneous x-axis and y-axis outputs. U.S. Pat. No. 4,444,998 also shows simultaneous outputs.